Question by dy: How does the nature of radio waves allow a radio telescope to use a wire mesh surface?
How does the nature of radio waves allow a radio telescope to use a wire mesh surface? Would you expect millimeter wavelength telescopes to need smoother surfaces than typical radio dishes? Why or Why not?
Answer by David Knisely
The relatively long wavelength of radio waves means that the openings in wire mesh are quite small when compared to the size of the wave, so the mesh can be a fairly efficient reflector of radio energy despite the small holes. Millimeter wavelength telescopes would need a smoother and more continuous surface due to the shorter wavelength of the millimeter waves. This is needed to focus the waves without surface irregularities scattering them away from the focal point. To focus properly, the surface must be smooth to an accuracy of 1/8th of the wavelength of the radio photons being collected by the telescope.
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